▎ 摘　　要

The orientation control of graphene overlayers on metal surface is an important issue which remains as a challenge in graphene growth on Ni surface. Here we have demonstrated that epitaxial graphene overlayers can be obtained by annealing a nickel carbide covered Ni(111) surface using in situ surface imaging techniques. Epitaxial graphene islands nucleate and grow via segregation of dissolved carbon atoms to the top surface at about 400 A degrees C. This is in contrast to a mixture of epitaxial and non-epitaxial graphene domains grown directly on Ni(111) at 540 A degrees C. The different growth behaviors are related to the nucleation dynamics which is controlled by local carbon densities in the near surface region.